Retention in OAT is associated with substantial reduction in all-cause and overdose mortality,111 whereas abundant observational evidence has associated discontinuation of OAT medications with high rates of return to unregulated opioid use275,276 and subsequent drug toxicity death.111,277,278 In reference to these findings, national and international clinical guidelines define OAT as an open-ended treatment.279 

The research on withdrawal management strategies to minimize the risk of relapse and related harms for patients who expressly request to discontinue OAT is limited to a small number of observational studies. For example, a 2012 population-based retrospective study involving participants who received methadone for OUD in BC (n=4,813) found that tapers that last more than 52 weeks had consistently higher odds of sustained success compared to tapers that took less than 12 weeks (OR=6.68; 95% CI: 5.13 – 8.70), regardless of time in treatment prior to initiating taper.280 The authors also found that a stepped tapering protocol, with dose decreases scheduled for 25–50% of the weeks, provided the highest odds of sustained success (vs. <25%: 1.61 (1.22–2.14)) which was defined as no treatment re-entry, opioid-related hospitalization, or mortality within 18 months following treatment completion. However, the authors noted that the overall rate of sustained success was very low (13%).280

A 2022 cohort study in Ontario (n=5,774) also explored taper characteristics that were associated with a lower risk of opioid overdose after discontinuation of OAT with buprenorphine/naloxone.281 The authors found that a treatment duration of longer than 1 year prior to initiating taper (vs. ≤1 year; aHR: 0.69; 95% CI: 0.48-0.997), lower rate of taper (≤2 mg per month vs >4 mg per month, aHR, 0.65; 95% CI, 0.46-0.91), and a slower taper protocol with dose decreases scheduled in 1.75% or less of days during the taper (aHR: 0.64; 95% CI: 0.43-0.93) were associated with reduced risk of opioid overdose.281 

Overall, available observational evidence suggests that longer duration of treatment prior to initiating a taper and a slower taper schedule may reduce the risk of return to unregulated opioid use.